refactor: forces

app/ecs/components/forces.js

@@ -4,6 +4,16 @@ export default class Forces extends Component {
   instanceFromSchema() {
     const {ecs} = this;
     return class ForcesInstance extends super.instanceFromSchema() {
+      applyForce({x, y}) {
+        this.$$forceX += x;
+        this.$$forceY += y;
+        ecs.markChange(this.entity, {
+          Forces: {
+            forceX: this.$$forceX,
+            forceY: this.$$forceY,
+          },
+        });
+      }
       applyImpulse({x, y}) {
         this.$$impulseX += x;
         this.$$impulseY += y;
@@ -17,6 +27,8 @@ export default class Forces extends Component {
     }
   }
   static properties = {
+    forceX: {type: 'float32'},
+    forceY: {type: 'float32'},
     impulseX: {type: 'float32'},
     impulseY: {type: 'float32'},
   };

app/ecs/systems/integrate-physics.js

@@ -24,9 +24,9 @@ export default class IntegratePhysics extends System {
       return;
     }
     Position.lastX = Position.$$x;
-    Position.$$x += elapsed * (Forces.$$impulseX);
+    Position.$$x += elapsed * (Forces.$$impulseX + Forces.$$forceX);
     Position.lastY = Position.$$y;
-    Position.$$y += elapsed * (Forces.$$impulseY);
+    Position.$$y += elapsed * (Forces.$$impulseY + Forces.$$forceY);
     this.ecs.markChange(
       entity.id, {
         Position: {